HOMEMADE CROSSHAIR EYEPIECE
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Last updated: 20 October 2007
Subject:	Renewing cross hairs
Sent:	Friday, October 19, 2007 08:42:46
From:	Steve at mmic (stephen.sales@nordnet.fr)
Back after some time away, pleased to see your site is still as good as
ever.

The Autumn's here and now's the time to renew those broken cross hairs
or convert a normal eyepiece to a cross hair one. I've used single
strands unwoven from glass cloth in the past but they do seem to get
brittle quite quickly so here's how it used to be done, modified
slightly for modern times.

You need two paperclips, a garden, and some glue (balsa cement or RS
general purpose adhesive will do).

Dismantle the eyepiece. Remove the carrier  and  mark it with as fine a
scribe line as possible  where the broken cross hairs sit. Clean off old
bits of adhesive. Now's a good time to clean up the lenses and touch up
any flaked off blacking.

Make yourself two gathering tools ('bows') by unbending the paperclips
into a U about twice as wide as the hair to replace.

Go and find a nice big spider's web. Wait for the dew to evaporate. Coat
the ends of the U by pushing them a short way into the open end of your
tube of adhesive and pick up a length of spider silk by touching it on
the gluey ends of your paperclip. Keep moving until the strand breaks
and you will have a nicely tensioned piece of silk held by your
paperclip. Do the same again with the other. Apologize to the spider if
necessary.

Now you need a good light (low angle Autumnal sunlight is good). Put the
carrier on a suitable stand (like a cotton reel) . Put two small drops
of glue on the location of one cross air and lower the bow with one of
your stolen bits of spider silk onto them. There's time to slide the
hair into place using the bow as a handle. When satisfied let go of the
bow so its weight keeps the hair tensioned. When the glue's set cut the
hair free and repeat the process with the other one.
 
All best wishes,
Steve Sales

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